The HP-67 emulator, completion of the transition to the new API

At this point, all that remains is to write an engine that understands the new API. It should push preformatted strings to the UI, tell it to repaint itself, and ask it for input, then pass the returned input back to the keypress-handling function.

The code for this is fairly straight-forward. It does have to keep track of old values of some state variables, so that it can know when to update state in the UI and when not to. The code looks like this:

This is checked into the git repository under the tag v2014-12-04. Also, I just realized that my tags hadn’t been going to the repository. They have to be explicitly pushed, by supplying the –tags switch to the git push command.